A composite storage server consists of multiple distributed storage sites for a selective storage of volume data within two or more of the distributed storage sites. Typically, each distributed storage site employs a job director and for any given storage job, one of the distributed storage sites serves as a single source copy site whereby its director, upon completion of the volume data being pushed to its cache, will pull the cached volume data from its cache to thereby push the cached volume data to any of the other distributed storage sites designated as copy target sites for purposes of the storage job.
Clearly, the single source copy site demands significant processing power to being able to pull and push the cached volume data to the copy target sites, particularly in view of a substantial number of copy target sites and any concurrent execution of other storage jobs within the composite storage server. Furthermore, each copy target site has a servant role in terms of being excluded from the decision process by the source copy site of when, where and how fast the volume data is pushed to each copy target site and therefore also demands significant processing power, particularly in view of any concurrent execution of other storage jobs within the composite storage server whereby a copy target site may or may not serve as a source copy site for one or more of those storage jobs. Therefore, it would be invaluable for a composite storage server to incorporate a technique for distributing the responsibility of storing volume data within the composite storage server among the distributed storage sites whereby each distributed storage site involved in the storage of the volume data within the composite storage server is an active participant.